A green one-pot method for simultaneous extraction and transesterification of seed oil catalyzed by a p-toluenesulfonic acid based deep eutectic solvent

•A green one-pot method for simultaneous extraction and transesterification of seed oil was proposed.•Novel p-toluenesulfonic acid based deep eutectic solvents were prepared successfully.•Central composite design (CCD) and response surface methodology were conducted.•High extraction and transesterification yields of oil demonstrated the eff ;ectiveness of the prepared catalyst. In this study, a novel p-toluenesulfonic acid (PTSA) based deep eutectic solvent (DES) was prepared successfully for biodiesel production by one-pot method. The DES consisting of PTSA and tetrabutylammonium bromide (TBAB) exhibited the best catalytic activity among the five prepared DESs. Central composite design (CCD) and response surface methodology were conducted to investigate reaction factors. The maximum oil extraction yield 90.33 % and fatty acid methyl esters (FAMEs) conversion yield 96.53 % were obtained under the optimal condition: microwave temperature 72 °C, microwave power 500 W, time 40 min, the ratio of liquid to seed weight 27:1 and DES amount 11 wt%. The chemical composition of FAMEs and main physical-chemical properties were investigated and the results demonstrated that the prepared biodiesel product possessed high quality. The study showed the prepared DES was a green and efficient catalyst for rapid and simultaneous extraction and transesterification seed oil for biodiesel production by one-pot method.